Remove the definition of AtomicOps_Internalx86CPUFeatures from base/atomicops_internals_tsan.h

As noted in https://codereview.chromium.org/10948035, this is not used by anyone in Chromium.

BUG=None
TBR=thakis@chromium.org

Review URL: https://codereview.chromium.org/339343002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@278081 0039d316-1c4b-4281-b951-d872f2087c98

base/atomicops_internals_tsan.h

@@ -8,22 +8,6 @@
 #ifndef BASE_ATOMICOPS_INTERNALS_TSAN_H_
 #define BASE_ATOMICOPS_INTERNALS_TSAN_H_
 
-#include "base/base_export.h"
-
-// This struct is not part of the public API of this module; clients may not
-// use it.  (However, it's exported via BASE_EXPORT because clients implicitly
-// do use it at link time by inlining these functions.)
-// Features of this x86.  Values may not be correct before main() is run,
-// but are set conservatively.
-struct AtomicOps_x86CPUFeatureStruct {
-  bool has_amd_lock_mb_bug;  // Processor has AMD memory-barrier bug; do lfence
-                             // after acquire compare-and-swap.
-};
-BASE_EXPORT extern struct AtomicOps_x86CPUFeatureStruct
-    AtomicOps_Internalx86CPUFeatures;
-
-#define ATOMICOPS_COMPILER_BARRIER() __asm__ __volatile__("" : : : "memory")
-
 #include <sanitizer/tsan_interface_atomic.h>
 
 namespace base {
@@ -199,6 +183,4 @@ inline void MemoryBarrier() {
 }  // namespace base::subtle
 }  // namespace base
 
-#undef ATOMICOPS_COMPILER_BARRIER
-
 #endif  // BASE_ATOMICOPS_INTERNALS_TSAN_H_